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Oral Delivery (Focus Group – OrD)

Using FD4 to Assess Caco‑2 Monolayer Integrity in GLP‑1 Permeation Studies

Exploring Oral GLP-1 Delivery: A Caco-2-Based In Vitro Formulation Approach

Alana Gouveia – Senior Scientist/ PhD Candidate, Merck Life Science KGaA/ University of Heidelberg; Zhizhou Fang – Associate Director, Merck Healthcare KGaA; Jason Tonillo – Lab Head, Merck Healthcare KGaA; Philipp Uhl – Professor, Heidelberg University; Gert Fricker – Professor, Heidelberg University
Introduction:

Reliable Caco‑2 data require verified monolayer integrity, especially tightness to ~4 kDa solutes. Paracellular leaks bias permeability and inflate Papp, skewing absorption estimates [9,10]. To qualify assays, we use a size‑matched control: FITC‑dextran 4 kDa (FD4), which approximates semaglutide’s mass and benchmarks barrier function. Confirming integrity with FD4 validates conditions and enables relevant comparisons. Literature supports FD4 for assessing Caco‑2 tight‑junction integrity [1,2,3].

Learning Objectives:

  • Define and apply FD4-based thresholds to qualify Caco‑2 monolayer integrity in permeation studies for GLP-1
  • Use FD4 to qualify Caco‑2 integrity and ensure reliable GLP‑1 Papp readouts.
  • CPP‑liposomes: aids uptake and permeation; size/PDI, EE, cytotoxicity on target.